This aperture series assesses the Leica 90mm f/2.2 Thamber-M from f/2.2 through f/6.3, while also adding in the Nikon 105mm f/2 DC (defocus control) whose DC control adds selective spherical aberration.

While the focal lengths are not a match, the question is: why not spend about $1000 on a much more versatile lens (the Nikon 105/2 DC) and skip the Thambar? The Thambar is not a coded lens for Leica, and so the fact that the Nikon 105/2 DC is not coded is of no relevance. It is used with a Nikon F to Leica M adapter.

This series shows large difference in bokeh style; some shooters might prefer the Nikon 105/2 DC, which is lovely in its own right and also a useful general purpose lens. But the Leica 90mm f/2.2 Thambar has a look all its own, too.